Glaucoma Treatment Method

ABSTRACT

An ocular implant adapted to reside at least partially in a portion of Schlemm&#39;s canal of an eye. In some embodiments the implant has a body extending in a curved volume whose longitudinal axis forms an arc of a circle, and a plurality of open areas and strut areas formed in the body, the open areas extending over more than 50% of a surface defining the curved volume, the strut areas surrounding the open areas, the body having a diameter of between 0.005 inches and 0.04 inches. The invention also provides a method of treating glaucoma including the steps of supporting tissue forming Schlemm&#39;s canal in an eye with an implant extending at least partially in the canal along an axial length within the canal; and contacting with the implant less than 50% of the tissue forming the canal along the axial length.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.11/860,318, filed Sep. 24, 2007, entitled “Ocular Implants”, whichapplication is incorporated by reference herein.

FIELD OF THE INVENTION

The present invention relates generally to devices that are implantedwithin the eye. More particularly, the present invention relates todevices that facilitate the transfer of fluid from within one area ofthe eye to another area of the eye.

BACKGROUND OF THE INVENTION

According to a draft report by The National Eye Institute (NEI) at TheUnited States National Institutes of Health (NIH), glaucoma is now theleading cause of irreversible blindness worldwide and the second leadingcause of blindness, behind cataract, in the world. Thus, the NEI draftreport concludes, “it is critical that significant emphasis andresources continue to be devoted to determining the pathophysiology andmanagement of this disease.” Glaucoma researchers have found a strongcorrelation between high intraocular pressure and glaucoma. For thisreason, eye care professionals routinely screen patients for glaucoma bymeasuring intraocular pressure using a device known as a tonometer. Manymodern tonometers make this measurement by blowing a sudden puff of airagainst the outer surface of the eye.

The eye can be conceptualized as a ball filled with fluid. There are twotypes of fluid inside the eye. The cavity behind the lens is filled witha viscous fluid known as vitreous humor. The cavities in front of thelens are filled with a fluid know as aqueous humor. Whenever a personviews an object, he or she is viewing that object through both thevitreous humor and the aqueous humor.

Whenever a person views an object, he or she is also viewing that objectthrough the cornea and the lens of the eye. In order to be transparent,the cornea and the lens can include no blood vessels. Accordingly, noblood flows through the cornea and the lens to provide nutrition tothese tissues and to remove wastes from these tissues. Instead, thesefunctions are performed by the aqueous humor. A continuous flow ofaqueous humor through the eye provides nutrition to portions of the eye(e.g., the cornea and the lens) that have no blood vessels. This flow ofaqueous humor also removes waste from these tissues.

Aqueous humor is produced by an organ known as the ciliary body. Theciliary body includes epithelial cells that continuously secrete aqueoushumor. In a healthy eye, a stream of aqueous humor flows out of theanterior chamber of the eye through the trabecular meshwork and intoSchlemm's canal as new aqueous humor is secreted by the epithelial cellsof the ciliary body. This excess aqueous humor enters the venous bloodstream from Schlemm's canal and is carried along with the venous bloodleaving the eye.

When the natural drainage mechanisms of the eye stop functioningproperly, the pressure inside the eye begins to rise. Researchers havetheorized prolonged exposure to high intraocular pressure causes damageto the optic nerve that transmits sensory information from the eye tothe brain. This damage to the optic nerve results in loss of peripheralvision. As glaucoma progresses, more and more of the visual field islost until the patient is completely blind.

In addition to drug treatments, a variety of surgical treatments forglaucoma have been performed. For example, shunts were implanted todirect aqueous humor from the anterior chamber to the extraocular vein(Lee and Scheppens, “Aqueous-venous shunt and intraocular pressure,”Investigative Opthalmology (February 1966)). Other early glaucomatreatment implants led from the anterior chamber to a sub-conjunctivalbleb (e.g., U.S. Pat. No. 4,968,296 and U.S. Pat. No. 5,180,362). Stillothers were shunts leading from the anterior chamber to a point justinside Schlemm's canal (Spiegel et al., “Schlemm's canal implant: a newmethod to lower intraocular pressure in patients with POAG?” OphthalmicSurgery and Lasers (June 1999); U.S. Pat. No. 6,450,984; U.S. Pat. No.6,450,984).

SUMMARY OF THE INVENTION

While some prior glaucoma treatment implants did provide a flow pathbetween the anterior chamber and Schlemm's canal, these prior devicesfailed to recognize (1) the importance of supporting a significantportion of Schlemm's canal in a patent state or (2) the harm to adjacenttissue caused by relatively high fluid flow rates at or around anyportion of the device. The ocular implant devices and methods of thisinvention address one or both of these design criteria.

According to one aspect of the invention, the ocular implant may beinserted into Schlemm's canal of an eye to facilitate the flow ofaqueous humor out of the anterior chamber of the eye by, e.g.,supporting tissue in the trabecular meshwork and in Schlemm's canal. Theflow facilitated by the presence of the ocular implant may include axialflow along Schlemm's canal, flow into Schlemm's canal from the anteriorchamber of the eye, and flow leaving Schlemm's canal via the outletsthat communicate with the canal.

After exiting Schlemm's canal via the outlets, aqueous humor enters thevenous blood stream and is carried along with the venous blood leavingthe eye. The pressure of the venous system tends to be around 5-10 mmHgabove atmospheric pressure. Accordingly, the venous system provides apressure backstop which assures that the pressure in the anteriorchamber of the eye remains above atmospheric pressure.

Some exemplary ocular implants disclosed in this document comprise abody having a plurality of open areas, strut areas and spine areasformed therein. The strut areas and spine areas act as reinforcingstructures that hold the walls of Schlemm's canal in an patent state sothat the walls of the canal provide a flow channel or fistula.Furthermore, the spine areas and the strut areas may be sized and shapedto reinforce Schlemm's canal while occupying a relatively small portionof the total lateral cross sectional area of Schlemm's canal. When thisis the case, the ocular implant provides minimal obstruction to aqueoushumor flowing along the length of Schlemm's canal. Reinforcing Schlemm'scanal with minimal metal mass present in the canal may also encourage asafe healing response over time.

Some exemplary ocular implants disclosed in this document comprise abody defining openings that are sized and shaped to facilitate thelateral flow of aqueous humor across and/or through the body of theocular implant. The lateral flow of aqueous humor may include the flowof aqueous humor through the trabecular mesh and into Schlemm's canal.The lateral flow of aqueous humor may also include the flow of aqueoushumor through outlets that communicate with Schlemm's canal.

One aspect of the invention provides an ocular implant adapted to resideat least partially in a portion of Schlemm's canal of an eye. In someembodiments, the ocular implant has a body extending in a curved volumewhose longitudinal axis forms an arc of a circle, and a plurality ofopen areas and strut areas formed in the body, the open areas extendingover more than 50% of a surface defining the curved volume, the strutareas surrounding the open areas, the body having a diameter of between0.005 inches and 0.04 inches.

In some embodiments, the open areas are formed in a first longitudinalsection extending along the curved volume. This longitudinal section mayinclude the largest radius portion of the curved volume. The open areasof the implant may also include a plurality of openings formed on asecond longitudinal section of the implant body disposed, e.g., oppositethe first longitudinal section. In addition, there may be spine sectionsdisposed between the openings formed on the second longitudinal section.

In some embodiments, the strut areas extend axially andcircumferentially around the body from one side of the firstlongitudinal section to the other side of the first longitudinalsection. Some of the open areas may be formed between the strut areas.

In some embodiments, the implant is formed from shape memory material ina shape approximately equal to the curved volume. The curved volume ofthe implant may extend through a 60°-180° arc of a circle. In someembodiments, material coverage within the curved volume in circularcross-sections perpendicular to the longitudinal axis is less than 50%over greater than 90% of the implant.

In some embodiments, the implant has an inlet portion disposed at oneend of the body in fluid communication with the body and extendinginward from the circle arc. The inlet portion may extend at a 90° anglefrom a tangent drawn from a connection point of the inlet portion to thebody. In some embodiments, the inlet portion has a length greater thanthe diameter of the body. The inlet portion may be formed, e.g., as acoil, a channel with at least one open longitudinal section, etc. influid communication with the body of the implant. The inlet portion mayalso extend along the same circle arc as the body.

In some embodiments, the implant may have a blunt tip disposed at oneend, and there may be a lumen formed through the blunt tip.

In some embodiments, a therapeutic agent may be deposited on the body ofthe implant. The therapeutic agent may be an anti-glaucoma drug such asa prostaglandin analog (e.g., latanoprost).

Another aspect of the invention provides a method of treating glaucomaincluding the following steps: supporting tissue forming Schlemm's canalin an eye with an implant extending at least partially in the canalalong an axial length within the canal; and contacting with the implantless than 50% of the tissue forming the canal along the axial length. Insome embodiments, the implant has open areas separated by spine areasalong a first longitudinal section, in which case the supporting stepincludes the step of orienting the first longitudinal section openingstoward a trabecular mesh portion of the canal. The supporting step mayalso include the step of orienting a second longitudinal section of theimplant which is at least 90% open opposite to the first longitudinalsection within the canal.

In some embodiments, the supporting step includes the step of supportingwith the implant tissue extending approximately 60°-180° around thecanal.

In some embodiments, the method includes the step of providing fluidcommunication between an anterior chamber and the canal through theimplant, such as by engaging trabecular mesh tissue with the implant.

In some embodiments, the supporting step includes the step of supportingthe tissue with the implant such that material coverage of tissue by theimplant in cross-sections of the implant perpendicular to a longitudinalaxis of the canal is less than 50% over greater than 90% of the axiallength of the implant.

In some patients, Schlemm's canal may have become compartmentalized.When this is the case, Schlemm's canal becomes a series of smallcompartments separated by discontinuities or partitions. As the ocularimplant is advanced into Schlemm's canal, the distal tip of the ocularimplant penetrates the discontinuities/partitions. This penetratingaction re-establishes fluid communication between adjacent compartments.The body of the ocular implant facilitates flow across the partitions byremaining in Schlemm's canal after fluid communication has beenre-established.

Some exemplary ocular implants disclosed herein include a blunt tiphaving a generally rounded shape. For example, the blunt tip may have agenerally hemispherical shape. The generally rounded shape of the blunttip may increase the likelihood that the body of the ocular implant willtrack Schlemm's canal as the ocular implant is advanced into the canalduring an implant procedure.

Some exemplary ocular implants disclosed in this document include aninlet portion that is shaped and sized to extend through the trabecularmeshwork of the eye. This inlet portion may provide a flow path betweenthe anterior chamber and Schlemm's canal. After entering Schlemm'scanal, aqueous humor may flow between a proximal portion of the ocularimplant and an intermediate portion of the ocular implant. Theintermediate portion of the ocular implant may be conceptualized as amanifold that distributes the aqueous humor along a portion of Schlemm'scanal. A plurality of outlets may be located along the length of thisportion of Schlemm's canal. When this is the case, the presence of theocular implant in Schlemm's canal facilitates the flow of aqueous humorthrough those outlets.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view showing a portion of an eye.

FIG. 2 is an enlarged plan view of a portion of the eye shown in theprevious figure.

FIG. 3 is a top plan view showing an intermediate portion of anexemplary ocular implant.

FIG. 4 is a sideplan view of the ocular implant shown in the previousfigure.

FIG. 5 is a lateral cross-sectional view of the ocular implant shown theprevious figure.

FIG. 6 is an additional lateral cross-sectional view of the ocularimplant shown the previous figure.

FIGS. 7A, 7B, and 7C are side, bottom and top plan views (respectively)illustrating an exemplary ocular implant.

FIGS. 8A, 8B, and 8C are additional, larger side, bottom and top planviews (respectively) of the exemplary ocular implant shown in FIGS. 7A,7B, and 7C.

FIG. 9 is an additional side plan view illustrating the ocular implantshown in the previous figure.

FIG. 10 is a top plan view illustrating the ocular implant shown in theprevious figure.

FIG. 11 is a perspective view of an exemplary ocular implant.

FIG. 12 is a plan view of an additional exemplary ocular implant.

FIGS. 13A, 13B, and 13C are side, bottom and top plan views(respectively) illustrating another exemplary ocular implant.

FIG. 14 is a perspective view of an ocular implant.

FIG. 15 is a side view of the ocular implant of FIG. 14.

FIG. 16 is a perspective view of yet another ocular implant.

FIG. 17 is a perspective view of still another ocular implant.

FIG. 18 shows the ocular implant of FIGS. 11 and 12 in place within apatient's eye.

FIG. 19 shows the ocular implant of FIGS. 14 and 15 in place within apatient's eye.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The following detailed description should be read with reference to thedrawings, in which like elements in different drawings are numberedidentically. The drawings, which are not necessarily to scale, depictexemplary embodiments and are not intended to limit the scope of theinvention. Examples of constructions, materials, dimensions, andmanufacturing processes are provided for selected elements. All otherelements employ that which is known to those of skill in the field ofthe invention. Those skilled in the art will recognize that many of theexamples provided have suitable alternatives that can be utilized.

FIG. 1 is a plan view showing a portion of an eye 20. A reflection onthe outer surface of the cornea 22 of eye 20 is visible in FIG. 1.Cornea 22 encloses an anterior chamber 24 of eye 20. The iris 26 of eye20 is visible through cornea 22 and anterior chamber 24. Anteriorchamber 24 is filled with aqueous humor which helps maintain thegenerally hemispherical shape of cornea 22.

Whenever a person views an object, he or she is viewing that objectthrough the cornea, the aqueous humor, and the lens of the eye. In orderto be transparent, the cornea and the lens can include no blood vessels.Accordingly, no blood flows through the cornea and the lens to providenutrition to these tissues and to remove wastes from these tissues.Instead, these functions are performed by the aqueous humor. Acontinuous flow of aqueous humor through the eye provides nutrition toportions of the eye (e.g., the cornea and the lens) that have no bloodvessels. This flow of aqueous humor also removes waste from thesetissues.

Aqueous humor is produced by an organ known as the ciliary body. Theciliary body includes epithelial cells that continuously secrete aqueoushumor. In a healthy eye, a stream of aqueous humor flows out of the eyeas new aqueous humor is secreted by the epithelial cells of the ciliarybody. This excess aqueous humor enters the blood stream and is carriedaway by venous blood leaving the eye. The structures that drain aqueoushumor from anterior chamber 24 include Schlemm's canal 30 and a largenumber of veins 28.

In FIG. 1, Schlemm's canal 30 can be seen encircling iris 26. Aqueoushumor exits anterior chamber 24 and enters Schlemm's canal 30 by flowingthrough a trabecular mesh 32. Aqueous humor exits Schlemm's canal 30 byflowing through a number of outlets 40. After leaving Schlemm's canal30, aqueous humor travels through veins 28 and is absorbed into theblood stream. Schlemm's canal typically has a non-circularcross-sectional shape whose diameter can vary along the canal's lengthand according to the angle at which the diameter is measured. Inaddition, there may be multiple partial pockets or partial compartments(not shown in these figures) formed along the length of Schlemm's canal.The shape and diameter of portions of Schlemm's canal and the existenceand relative location of partial pockets or compartments may limit orprevent fluid flow from one point of Schlemm's canal to another. Hence,each outlet 40 from Schlemm's canal may drain only a portion ofSchlemm's canal.

FIG. 2 is an enlarged plan view of a portion of eye 20 shown in theprevious figure. The flow of aqueous humor in eye 20 is illustratedusing arrows in FIG. 2. In FIG. 2, aqueous humor flowing throughtrabecular mesh 32 and into Schlemm's canal 30 is represented by anumber of lateral flow arrows 34. The flow of aqueous humor along thelength of Schlemm's canal is illustrated using a number of axial flowarrows 36.

With reference to FIG. 2, it will be appreciated that a number ofoutlets 40 communicate with Schlemm's canal 30. In FIG. 2, the flow ofaqueous humor exiting Schlemm's canal 30 and flowing through outlets 40is illustrated with additional lateral flow arrows 34. After leavingSchlemm's canal 30, aqueous humor travels through veins 28 and isabsorbed into the blood stream.

FIGS. 3 and 4 are top and side views showing an intermediate portion ofan exemplary ocular implant 100. Ocular implant 100 may be inserted intoSchlemm's canal, the trabecular meshwork and the anterior chamber tofacilitate the outflow of aqueous humor from the anterior chamber. Thisflow may include axial flow along Schlemm's canal, flow from theanterior chamber into Schlemm's canal, and flow leaving Schlemm's canalvia outlets communicating with Schlemm's canal. When in place within theeye, ocular implant 100 will support trabecular mesh tissue andSchlemm's canal tissue and will provide for improved communicationbetween the anterior chamber and Schlemm's canal (via the trabecularmeshwork) and between pockets or compartments along Schlemm's canal.

Ocular implant 100 of FIGS. 3 and 4 comprises a body 104 having an outersurface 106. Body 104 of ocular implant 100 has a plurality of pairs ofstruts 120 and 122 separated by spine sections 124. The struts andspines define an open channel 134 whose open side lies along onelongitudinal section of the implant body. A plurality of openings 130are formed between the struts 120 and 122 on a longitudinal section ofthe implant opposite to the open side of channel 134. While in thisembodiment the openings 130 are 180° from the open side of channel 134,in other embodiments openings 130 may be disposed 140°-150° the openside of channel 134. The diameter of body 104 is selected to support thetissue of Schlemm's canal without stretching it and is preferably in therange of 0.005 inches to 0.04 inches, most preferably in the range of0.005 inches to 0.02 inches.

As shown in these figures, aqueous humor may flow axially down openchannel 134 (as shown by arrows 36 in FIG. 4) or out of the implantthrough the opening of open channel 134 (first passing, e.g., throughopenings 130 and/or along the channel 134) as represented by lateralflow arrows 34. When implanted, body 104 of implant 100 preferablyextends 60°, 90°, 150° or 180° around the circle formed by Schlemm'scanal. The arrangement of struts, open areas and spine areas alongimplant 100 supports the tissue of Schlemm's canal with a minimum amountof material. In the embodiment shown in FIGS. 3 and 4, for example, theopen areas extend over more than 50% of a hypothetical surface coveringthe volume of the portion of the implant lying within Schlemm's canal.This combination of features helps aqueous humor flow between anypockets or compartments formed within Schlemm's canal and, therefore,between the anterior chamber and the outlets from Schlemm's canal to thevenous system.

FIG. 5 is a lateral cross-sectional view of ocular implant 100 takenalong line 5-5 shown in FIG. 4, and FIG. 6 is a lateral cross-sectionalview of ocular implant 100 taken along line 6-6 shown in FIG. 4. Thereare normally many flow paths from the anterior chamber through thetrabecular meshwork into Schlemm's canal. Aqueous humor may thereforeflow into channel 134 in body portion 104 of implant 100 from thetrabecular meshwork through one or more openings 130 and/or around thestruts 120/122 and spines 124. Thus, in FIG. 5, aqueous humor flowingpast a spine area 124 is illustrated with lateral flow arrows 34, and inFIG. 6, aqueous humor flowing between first strut area 120 and secondstrut area 122 is illustrated using lateral flow arrows 34.

FIGS. 5 and 6 also illustrate another unique feature of implant 100: Thearrangement of struts, openings and spine areas ensures that materialcoverage of Schlemm's canal in virtually any cross-section of theimplant and canal is less than 50%. This material coverage relationshiphold true for over 90% of the implant's length.

In some embodiments, in addition to a Schlemm's canal portion asdescribed above, the ocular implant also includes at least one optionalinlet portion adapted to be disposed in the anterior chamber of the eye.The inlet portion is configured to support trabecular mesh tissue and topermit aqueous humor to flow from the anterior chamber into the openchannel of the implant within Schlemm's canal. FIGS. 7A-C and 8A-Cillustrate an exemplary ocular implant 100 with an optional inlet region150 in addition to a plurality of struts 120, 122, openings 130 andspine areas 124 substantially the same as the previous embodiment. Inthe embodiment of FIGS. 7 and 8, inlet region 150 of ocular implant 100comprises a coil. Coil 150 comprises a plurality of turns 152 that aredefined by a generally helical slot 154. Coil 150 may be bent so as toproject through the trabecular mesh into the anterior chamber while theremainder of the device lies within Schlemm's canal. Aqueous humor canflow into the inlet region through an open end 148 and through slot 154.

In some embodiments, the ocular implant may have an optional blunt tipfor use in facilitating atraumatic delivery of the device into Schlemm'scanal. As shown in FIGS. 7 and 8, distal portion 140 of ocular implant100 comprises a blunt tip 142. In some useful embodiments of ocularimplant 100, blunt tip 142 has a generally rounded shape. In theembodiment shown in FIGS. 7 and 8, blunt tip 142 has a generallyhemispherical shape.

In the embodiment of FIGS. 7 and 8, body 104 of ocular implant 100 ispictured assuming a generally straight shape. Embodiments of ocularimplant 100 are possible in which body 104 has a generally curvedresting shape.

Ocular implant 100 can be fabricated, for example, by providing a tubeand laser cutting openings in the tube to form the shape shown in FIGS.7 and 8. Body 104 of ocular implant 100 can be fabricated from variousbiocompatible material possessing the necessary structural andmechanical attributes. Both metallic and non-metallic materials may besuitable. Examples of metallic materials include stainless steel,tantalum, gold, titanium, and nickel-titanium alloys known in the art asNitinol. Nitinol is commercially available from Memry Technologies(Brookfield, Conn.), TiNi Alloy Company (San Leandro, Calif.), and ShapeMemory Applications (Sunnyvale, Calif.).

Ocular implant 100 may include a therapeutic agent deposited on body104. The therapeutic agent may, for example, be incorporated into apolymeric coating that is deposited out the outer surface 106 of body104. The therapeutic agent may comprise an anti-glaucoma drug. Examplesof anti-glaucoma drugs include prostaglandin analogs. Examples ofprostaglandin analogs include latanoprost.

Ocular implant 100 may be used in conjunction with a method of treatinga patient. Some such methods may include the step of inserting a coremember into a lumen defined by ocular implant 100. The core member maycomprise, for example, a wire or tube. The distal end of the ocularimplant may be inserted into Schlemm's canal. The ocular implant and thecore member may then be advanced into Schlemm's canal until the ocularimplant has reached a desired position. The core member may then bewithdrawn from the ocular implant.

FIGS. 9 and 10 show another embodiment of an ocular implant 100 similarto that of FIGS. 7 and 8. With reference to FIGS. 9 and 10, a lumen 156is formed in blunt tip 142. This lumen may be used to inject a contrastmedium through the blunt tip during implantation of the implant into thepatient's eye. Lumen 156 may also be used to inject a visco-elasticmedium in front of the implant to part tissue as the implant moves intoSchlemm's canal.

A dotted line 160 in FIGS. 9 and 10 indicates a cylindrical envelopesurrounding implant 100. In some embodiments, the open areas of ocularimplant 100 (made up of openings 130 and the open portion of openchannel 134) extend over more than 50% of cylindrical surface 160.

FIGS. 11 and 12 show an additional exemplary ocular implant 200according to the invention. In the embodiment of FIGS. 11 and 12, noexternal forces are acting on ocular implant 200, and ocular implant 200is free to assume a generally curved resting shape in which itslongitudinal axis forms an arc of a circle 266, as depicted in FIGS. 11and 12. In some useful embodiments of ocular implant 200, a relativelystiff core may be placed in the ocular implant 200 to cause it to assumea generally straight shape during delivery.

As shown in FIGS. 11 and 12, implant 200 has a plurality of openings 230along a longitudinal section on a shorter radius side of the body, aswell as an open channel 234 facing radially outward on a longitudinalsection forming the largest radius portion of the body. As in the priorembodiments, implant 200 also has a plurality of struts 236 and spineareas 224 formed in the body portion 204 of the implant. As shown, theopen areas (including the openings 230 and the open portion of channel234) extend over more than 50% of the surface of a hypothetical cylinder256 surrounding the implant 200. In addition, material coverage ofSchlemm's canal in cross-sections taken over 90% of the length ofimplant 200 is less than 50%, as in the previous embodiment.

Ocular implant 200 of FIGS. 11 and 12 includes an inlet portion 268extending inward from circle 266. Inlet portion 268 of ocular implant200 comprises a coil 250 having a plurality of turns 252 that aredefined by a generally helical slot 254. An inlet 274 is formed in oneend of inlet portion 268. Inlet portion 268 will extend through thetrabecular meshwork into the anterior chamber of the eye when bodyportion 204 lies in Schlemm's canal.

Ocular implant 200 of FIGS. 11 and 12 includes a blunt tip 242 with agenerally rounded shape. The generally rounded shape of blunt tip 242may increase the likelihood that body 204 will track Schlemm's canal asocular implant 200 is advanced into the canal during an implantprocedure.

As shown in FIGS. 11 and 12, ocular implant 200 extends through a 180°arc of circle 366. Other implant sizes are possible, of course, such asimplants extending 60°, 90° and 150° around a circle. As shown in FIG.12, inlet portion 268 is shown extending at an angle A from a tangentline T. In the embodiment of FIG. 13, angle A is about 90 degrees. Inletportion 268 has a length L and body 204 of ocular implant 300 has adiameter D. In the embodiment of FIG. 12, length L is greater thandiameter D. As in the other embodiments, the diameter can range from0.005 inches to 0.04 inches, preferably from 0.005 inches to 0.02inches, in order to lie within and support Schlemm's canal.

FIG. 18 shows the implant of FIGS. 11 and 12 in place within a patient'seye. The body portion (including the plurality of strut pairs 236,openings 230, open channel 234, spine areas 224 and the blunt tip 242)lie within and support the walls of Schlemm's canal 284. The openings230 are oriented at least partially toward the trabecular meshwork 282,and the open portion of open channel 234 is oriented on the largestradius portion of the canal facing openings 286 from Schlemm's canalinto the venous system (not shown). As shown, the body of the implantextends approximately 180° around the canal. The inlet portion 250 ofthe implant extends through the trabecular meshwork 282 into theanterior chamber 280 so that the inlet 274 and spiral slot 254 are influid communication with the aqueous humor within the anterior chamber.

FIGS. 13A-C show an additional exemplary ocular implant 400. As in theembodiments shown above, ocular implant 400 comprises a body 404 havinga plurality of openings 430, an open channel 434, pairs of struts 420and 422, and spine areas 424. As in the earlier embodiments, the openareas (including the openings 430 and the open portion of channel 434)extend over more than 50% of a hypothetical cylinder surrounding thebody portion 404 of implant 400, and material coverage of Schlemm'scanal in cross-sections taken over 90% of the length of the implant 400is less than 50%. A blunt tip 442 is also provided, as in the earlierembodiments.

The inlet portion 450 of the implant differs from prior embodiments,however. Inlet portion 450 is formed as an open channel 476. When thebody portion 404 of the implant is disposed in Schlemm's canal and inletportion 150 projects through the trabecular meshwork into the anteriorchamber, aqueous humor can flow into the implant through the openchannel 476 and then into the body portion 404 within Schlemm's canal.The open nature of inlet portion 450 reduces the speed with whichaqueous humor will flow into the implant, thereby reducing potentialdamage to adjacent tissue from suction forces associated with the flow.

FIGS. 14 and 15 show embodiments similar to that of FIG. 13 in which theimplant 400 has an at rest shape in the form of an arc of a circle. Asin the earlier embodiments, the implant may extend around any portion ofthe circle, such as 60°, 90°, 150° or 180°. For example, the implant ofFIGS. 14 and 15 extends in a 150° arc, an implant 500 extending in a 60°arc is shown in FIG. 16, and an implant 600 extending in a 90° arc isshown in FIG. 17.

Unlike the embodiment shown in FIGS. 11 and 12, however, inlet portion450 lies along the same circle arc as the rest of the implant. Wheninlet portion 450 is disposed in the anterior chamber (as shown in FIG.19) and the other portions of the implant lie in Schlemm's canal, thedirection of axial flow of aqueous humor from inlet 450 into openchannel 434 does not change as dramatically as in embodiments in whichthe inlet portion is at a 90° angle to the body portion of the implant.

FIG. 19 shows the implant of FIGS. 14 and 15 in place within a patient'seye. The body portion (including the plurality of strut pairs 420,openings 430, open channel 434, spine areas 424 and the blunt tip 442)lie within and support the walls of Schlemm's canal 484. The openings430 are oriented at least partially toward the trabecular meshwork 482,and the open portion of open channel 434 is oriented on the largestradius portion of the canal facing openings 486 from Schlemm's canalinto the venous system (not shown). As shown, the body of the implantextends approximately 150° around the canal. The inlet portion 450 ofthe implant extends through the trabecular meshwork 482 into theanterior chamber 480 so that the open channel 476 of the inlet portionis in fluid communication with the aqueous humor within the anteriorchamber.

While exemplary embodiments of the present invention have been shown anddescribed, modifications may be made, and it is therefore intended inthe appended claims to cover all such changes and modifications whichfall within the true spirit and scope of the invention.

1. A method of treating glaucoma comprising: supporting tissue formingSchlemm's canal in an eye with an implant extending at least partiallyin the canal along an axial length within the canal; and contacting withthe implant less than 50% of the tissue forming the canal along theaxial length.
 2. The method of claim 1 wherein the implant comprisesopen areas separated by spine areas along a first longitudinal section,the supporting step comprising orienting the first longitudinal sectionopenings toward a trabecular mesh portion of the canal.
 3. The method ofclaim 2 wherein the supporting step further comprises orienting a secondlongitudinal section of the implant which is at least 90% open oppositeto the first longitudinal section within the canal.
 4. The method ofclaim 1 wherein the supporting step comprises supporting with theimplant tissue extending approximately 60°-180° around the canal.
 5. Themethod of claim 1 further comprising providing fluid communicationbetween an anterior chamber and the canal through the implant.
 6. Themethod of claim 5 wherein the step of providing fluid communicationcomprises engaging trabecular mesh tissue with the implant.
 7. Themethod of claim 1 wherein the supporting step comprises supporting thetissue with the implant such that material coverage of tissue by theimplant in cross-sections of the implant perpendicular to a longitudinalaxis of the canal is less than 50% over greater than 90% of the axiallength of the implant.